they exist in a symbiotic rela
tionship with gardens of bacte
ria living in their interior sac.
The red hemoglobin in a
worm's plume has components
that bind hydrogen sulfide from
vent fluids and carry it to the
bacteria within. The bacteria
have the ability to oxidize the
hydrogen sulfide and convert
large amounts of carbon dioxide
from seawater into organic car
bon. The carbon is absorbed by
the worms in a process that we
do not yet understand. The
question also remains as to how
the tube worms acquire the bac
teria in the first place.
Other bacteria living freely
outside a host provide fodder
for tiny crustaceans. Whenever
we used a "slurp gun" to suck
up bacteria samples for study,
we also captured hundreds of
minute crustaceans feeding on
the microbes.
Tube worms have distinct
but indistinguishable-sexes,
and we and our colleagues
observed them spawning on sev
eral occasions. Females expel
clouds of eggs, males puffs of
sperm. We were amazed to see
that these animals had grown to
sexual maturity and were
spawning in only 21 months.
Many questions about vent
ecology are still unanswered.
How, for instance, do bivalves
and attached worms colonize
vents? Do their larvae float
from nearby vents? The East
Pacific Rise is continuous from
the Galapagos region to the
Gulf of California, and we find
many of the same species from
one vent area to the next.
Are some larvae able to ride
on currents for great distances,
delaying metamorphosis to
adulthood until chemicals from
vents cue them to settle and
grow? We hope clues to relation
ships among far-flung vents will
come from genetic studies of
vent creatures.
In the meantime, we continue
to study the 300 new species
in 90 new genera, 20 new fam
ilies, and one new phylum-that
we have already sampled and
identified.